1. Field of the Invention
This invention relates to stabilized distillate fuel oils. More particularly, this invention relates to inhibiting color deterioration and particulate formation in distillate fuel oils, such as diesel fuel.
2. Description of the Prior Art
Various middle distillate fuel oils, such as diesel fuel and kerosene, tend to deteriorate with time. This deterioration usually results in the formation of sediment, sludge, or gum and objectionable color deterioration. Sediment formation may cause clogging of fuel system equipment such as filters, screens, nozzles, burners and other associated equipment. Discoloration of distillate fuel oils is objectionable for various reasons, including customer's preference for light colored fuel oils because discoloration may indicate that deterioration has occurred.
Suggestions of the prior art for stabilizing fuel oils include U.S. Pat. No. 2,256,187, Bartram, which discloses the use of a condensation product of a phosphorous halide and an organic hydroxyl containing compound, with the preferred class of materials comprising esters of phosphorous acids, to increase the stability of a relatively unstable oil product. Also, U.S. Pat. No. 2,261,227, Cloud, discloses the use of certain organic phosphites as stabilizing ignition promoters of diesel fuel. U.S. Pat. No. 2,943,924, Kukin, discloses fuel oil compositions obtained by incorporating in a mixture of certain catalytically cracked and straight-run distillate fuel oils a sludge inhibiting amount of a combination of (a) a certain monocarboxylic acid, and (b) a certain alkaline earth metal salt of an alkylbenzene sulfonic acid. U.S. Pat. No. 2,993,766, Fowler, teaches that the tendency of aviation gas turbine fuels to deposit carbonaceous matter at elevated temperatures may be inhibited by the presence of naphthenic acids in proportions above 0.1% based on the total fraction.
However, none of these prior art references disclose the unique and effective mixture of a phosphite compound and a carboxylic acid in accordance with the instant invention for inhibiting the color degradation and particulate formation of distillate fuel oils.